When I end a sentence with Jr., how do I also show that it is the end of the sentence?
good question! Just use one period
I don't like your premise of challenging the appropriateness of MLK day. Even the groundhog has a holiday, so... if you want a civil rights day, start one without messing with MLK day. It's important! :-D
You are right to capitalize Xerox, i think. You could ust say "photocopied."
a soon-to-be-obsolete observance that leaves more people wondering why they did not receive any mail on the second Tuesday of October than anything else.--- hahahh this is funny.
Celebrating Dr. King's birthday pushes other civil rights leaders to the background. -- i disagree!
Early abolitionists like Harriet Tubman and Frederick Douglass risked their lives to help the enslaved -----good points here, maybe I am wrong... you are starting to persuade me, but only a little.
Well your structure is great, with good topic sentences and a clear argument. But... instead of challenging the appropriateness of MLK day it would be better to suggest the addition of an additional holiday, "Civil Rights Day." That's what I think, I guess. The person grading you might grade harshly if s/he thinks it is heinous to challenge King's worthiness of a holiday. Asking for a Civil Rights Day and challenging the appropriateness of MLK day are 2 different things.